Effect of plant growth regulator on in vitro culture of Nelumbo nucifera Gaertn.

Study on effects of three kinds of cytokinin on shoot multiplication of Nelumbo nucifera Gaertn. was conducted by using shoot apex from young seedlings. The explants were cultured on solid Murashige and Skoog (1962) (MS) medium supplemented with 6-benzyladenine (BA), 6-furfurylamino purine (kinetin) and N-phenyl-N'-1,2,3-thiadizol-5-yl urea (TDZ) at the concentration of 0, 0.25, 0.5, 1 and 2 mg/l. The cultural condition were at 25+-2 deg C, 16 hrs light/8 hrs dark and for 8 weeks. BA at various concentrations showed significantly increased in shoot multiplication. The highest number of 11.1 and 11.6 shoots were obtained from 1 and 2 mg/l BA which were not significant differences. Number of leaves, length of leaves and petioles of new shoots were clearly decreased compared to MS that without BA. Kinetin had no effect on shoot multiplication. For TDZ at 0.25-2 mg/l inhibited shoot growth. When reduced the concentration to 0, 0.025, 0.05, 0.1 and 0.2 mg/l, TDZ could induced shoot multiplication. However, the result was not better than using BA. For callus induction, cotyledons obtained from young seeds at the age of 7 days after flowering were cut longitudinally into two pieces and cultured on solid MS medium to study effect of auxin; napthalene acetic acid (NAA), 2,4-dichlorophenoxy acetic acid (2,4-D) and 3,6-dichloro-o-anisic acid (dicamba) at the concentration of 0, 1, 5, 10 and 15 mg/l under both light and dark conditions. After 4 weeks, the results indicated that NAA at 5 mg/l under dark condition gave better result than the others with 40 percent callus formation. However, the callus were friable and hyperhydric with brown colour. In addition, young seeds at the age of 7 days after flowering were cultured on MS medium for a study on effects of auxin, as studied in cotyledon, at the concentration of 0, 1, 3, 5 and 10 mg/l. After 8 weeks, the result showed that NAA could induced callus more effectively than dicamba, but only small amount of callus were produced. 2,4-D had no effect on callus induction. Each auxin was also used in combination with 0.01 mg/l TDZ and gave better result in callus formation. The 100 percent of callus induction with highest amount of callus was found at 3 mg/l NAA supplemented with TDZ under light condition. However, the calli were friable, greenish-brown and hyperhydric. New shoots were isolated and roots were induced on MS medium supplemented with 0, 0.5, 1, 2 and 4 mg/l NAA or indolebutyric acid (IBA) for 4 weeks. Nonsignificant difference in root formation were found. However, 2 mg/l NAA induced 3.3 roots with more lateral roots. The plantlets were trans planted to flooded-mud growing medium for 4 weeks with 30 percent survival rate.